Phased micro analyzer IV

ABSTRACT

A fluid analyzer having a concentrator and separator for concentrating and separating fluid samples at pressures up to about 10,000 psi (˜700 bar). The concentrator and separator may consist of a solid-state thin-film heater-adsorber and a channel supported by a solid substrate. The concentrator may have numerous heated interactive elements for adsorbing and desorbing constituents of a sample fluid. The interactive elements may be heated in a time phased sequential manner by heaters. The separator may separate the sample fluid by compound. There may be thermal conductivity detectors, a flow sensor and electrical conductivity detectors proximate to the channels. This system of concentrator, separator, heaters and sensor may provide information about the sample fluid composition. A pump may be connected to the channel to move the sample fluid through it.

The present application claims priority under 35 U.S.C. § 119(e) (1) toco-pending U.S. Provisional Patent Application No. 60/440,108, filedJan. 15, 2003, and entitled “PHASED-III SENSOR”, wherein such documentis incorporated herein by reference. The present application also claimspriority under 35 U.S.C. § 119(e) (1) to co-pending U.S. ProvisionalPatent Application No. 60/500,821, filed Sep. 4, 2003, and entitled“PHASED V, VI SENSOR SYSTEM”, wherein such document is incorporatedherein by reference. The present application claims priority as acontinuation-in-part to co-pending U.S. Nonprovisional application Ser.No. 10/672,483, filed Sep. 26, 2003, and entitled “PHASED MICRO ANALYZERV, VI”, which claims the benefit of U.S. Provisional Application No.60/414,211, filed Sep. 27, 2002, wherein the co-pending U.S.Nonprovisional application Ser. No. 10/672,483 is incorporated herein byreference.

BACKGROUND

The present invention pertains to detection of fluids. Particularly, theinvention pertains to a phased heater array structure, and moreparticularly to application of the structure as a sensor for theidentification and quantification of fluid components. The term “fluid”may be used as a generic term that includes gases and liquids asspecies. For instance, air, gas, water and oil are fluids.

Aspects of structures and processes related to fluid analyzers may bedisclosed in U.S. Pat. No. 6,393,894 B1, issued May 28, 2002, to UlrichBonne et al., and entitled “Gas Sensor with Phased Heaters for IncreasedSensitivity,” which is incorporated herein by reference; U.S. Pat. No.6,308,553 B1, issued Oct. 30, 2001, to Ulrich Bonne et al., and entitled“Self-Normalizing Flow Sensor and Method for the Same,” which isincorporated herein by reference; and U.S. Pat. No. 4,944,035, issuedJul. 24, 1990, to Roger L. Aagard et al., and entitled “Measurement ofThermal Conductivity and Specific Heat,” which is incorporated herein byreference.

Presently available gas composition analyzers may be selective andsensitive but lack the capability to identify the component(s) of asample gas mixture with unknown components, besides being generallybulky and costly. The state-of-the-art combination analyzers GC-GC andGC-MS (gas chromatograph-mass spectrometer) approach the desirablecombination of selectivity, sensitivity and smartness, yet are bulky,costly, slow and unsuitable for battery-powered applications. In GC-AED(gas chromatograph-atomic emission detector), the AED alone uses morethan 100 watts, uses water cooling, has greater than 10 MHz microwavedischarges and are costly.

The phased heater array sensor may have separate chips for theconcentrator, the separator, as well as for an off-chip flow sensor.However, these may be integrated onto one chip and provide improvementsin the structural integrity and temperature control while reducing powerconsumption. The next phased heater array sensor involved an addition ofintegratable, micro-discharge devices for detection, identification andquantification of analyte. However, short of the full integration of theFET switches and shift register(s) onto the chip, there still was a needto wire-bond, route, connect and route about 110 wires from adaughter-board to mother-board with its micro-processor-controlled FETswitches, which caused bulk and labor cost. In addition, the phasedheater array sensor analyzers and conventional GCs seem to lackflexibility to change preconcentration and separation capabilitieson-line.

Detection, identification and analysis of very small amounts of fluidsin a less costly and more efficient manner are desired. Liquidchromatography analyzers of the related art are not portable, consumemuch power, and are slow and rather costly. However, eighty percent ofthe samples that need analyzing are liquid (e.g., medical, pharma, foodand water quality, drug testing and industrial), for which related-artanalyzers would not be well suited, especially if the differentialpressures get into the 50 pounds per square inch (psi) to 10,000 psi(˜3.5 to 700 bar) range.

SUMMARY

The present micro analyzer is a phased analyzer having improvedstructural integrity, featuring practically unlimited pressure range(similar to the pressure limits for quartz capillaries) and havingvirtually no leakage problems. Relative to conventional HPLC/CLCanalyzers, the present analyzer may be much more affordable (e.g., saveslabor and equipment amortization costs), faster and more versatilebecause it may be suitable for either liquid or gas sample analysis.

The heater elements may be energized in a time-phased sequence; they mayin an abbreviated sense be regarded as “phased heaters”, a “phasedheater array”, a “phased analyzer”, a “phased sensor” and so forth. Ananalyzer or sensor with such heaters and an associated interactiveelement arrangement for developing and increasing the size of aconcentration pulse as it moves past a number of heaters may be regardedas a “phased heater array structure for enhanced detection”, orrespectively designated with an acronym “PHASED”.

The sensor system/micro analyzer may consist of an array of selective,sensitive, fast and low-power PHASED heater elements in conjunction withan array of compact, fast, low-power, ambient pressure, minimal pumpingspectral analysis devices to achieve fluid component presence,identification and quantification.

The micro fluid analyzer may have a concentrator and two or moreseparators. The analyzer may have one, two or more pumps. The analyzermay have a hyper pre-concentrator having a number of channels. There arenumerous detectors positioned along the flow path of the analyzer. Also,one or more orifices and micro valves may be positioned in the flowpath. The analyzer may be configured as a multiple fluid or gaschromatograph.

The concentrator may have an array of PHASED heater elements thatprovide a heat pulse that moves along the fluid path to provide anincreasing concentration of heat in a sample fluid stream. Interactiveelements may be spaced along and exposed to the sample fluid stream.Each of the interactive elements may include an interactive substancethat may adsorb and desorb constituents of the fluid stream depending onthe temperature of the interactive element. Each interactive element mayhave a heater element in thermal communication with it. A controller maybe coupled to the heater elements for energizing the heater elements ina time-phased sequence. The controller may energize a first heaterelement with a first energy pulse, then energize a second heater elementthat is located downstream of the first heater element with a secondenergy pulse, and so on. The corresponding interactive elements maysequentially become heated and desorb selected constituents into thesample fluid stream. The first element may produce a first concentrationpulse that is carried by the sample fluid stream downstream toward thesecond heater element, and that heater element may be energized and heatthe second interactive element when the first concentration pulsereaches that interactive element. Here, the first energy pulse and thesecond energy pulse sequentially result in a larger compositeconcentration temperature pulse in the fluid stream, which moves on downthe channel of the concentrator to be further increased in size withsubsequent elements.

Additionally, flexibility, low cost and compactness features areincorporated via FET switches, shift registers and control logic ontothe same or a separate chip connected to the phased heater array sensorchip via wire-bonds or solder-bumps on the daughter-PCB (printed circuitboard connected to the mother-PCB via only about ten leads) andproviding the user flexibility to be able select the fraction of totalheatable elements for preconcentration and separation; and selection ofanalysis logic.

Multi-fluid detection and analysis may be automated via affordable,in-situ, ultra-sensitive, low-power, low-maintenance and compact microdetectors and analyzers, which can wirelessly or by another medium(e.g., wire or optical fiber) send their detection and/or analysisresults to a central or other manned station. A micro fluid analyzer mayincorporate a phased heater array, concentrator, separator and diverseapproaches. The analyzer may be capable of detecting a mixture of tracecompounds in a host or base sample gas or of trace compounds in a hostliquid.

The fluid analyzer may include a connective configuration to anassociated microcontroller or processor. An application of the sensormay include the detection and analyses of air pollutants in aircraftspace such as aldehydes, butyric acid, toluene, hexane, and the like,besides the conventional CO₂, H₂O and CO. Other sensing may includeconditioned indoor space for levels of gases such as CO₂, H₂O,aldehydes, hydrocarbons and alcohols, and sensing outdoor space andprocess streams of industries such as in chemical, refining, productpurity, food, paper, metal, glass and pharmaceutical industries. Also,sensing may have a significant place in environmental assurance andprotection. Sensing may provide defensive security in and outside offacilities by early detection of chemicals before their concentrationsincrease and become harmful.

A vast portion of the sensor may be integrated on a chip withconventional semiconductor processes or micro electromechanical system(MEMS) techniques. This kind of fabrication results in small, low-powerconsumption, and in situ placement of the micro analyzer. The flow rateof the air or gas sample through the monitor may also be very small.Further, a carrier gas for the samples is not necessarily required andthus this lack of carrier gas may reduce the dilution of the samplesbeing tested, besides eliminating the associated maintenance and bulk ofpressurized gas-tank handling. This approach permits the sensor toprovide quick analyses and prompt results, may be at least an order ofmagnitude faster than some related art devices. It avoids the delay andcosts of labor-intensive laboratory analyses. The sensor is intelligentin that it may have an integrated microcontroller for analysis anddetermination of gases detected, and may maintain accuracy, successfullyoperate and communicate information in and from unattended remotelocations. The sensor may communicate detector information, analyses andresults via utility lines, or optical or wireless media, with thecapability of full duplex communication to a host system over asignificant distance with “plug-and-play” adaptation and simplicity. Thesensor may be net-workable. It may be inter-connectable with other gassample conditioning devices (e.g., particle filters, valves, flow andpressure sensors), local maintenance control points, and can providemonitoring via the internet. The sensor is robust. It can maintainaccuracy in high electromagnetic interference (EMI) environments havingvery strong electrical and magnetic fields. The sensor has highsensitivity. The sensor offers sub-ppm (parts-per-million) leveldetection which is 100 to 10,000 times better than related arttechnology, such as conventional gas chromatographs which may offer asensitivity in a 1 to 10 ppm range. The sensor is, among other things, alower-power, faster, and more compact, more sensitive and affordableversion of a gas chromatograph. It may have structural integrity andhave very low or no risk of leakage in the application of detecting andanalyzing pressurized fluid samples over a very large differentialpressure range.

In the sensor, a small pump, such as a Honeywell Mesopump™, may draw asample into the system, while only a portion of it might flow throughthe phased heater sensor at a rate controlled by the valve (which may bea Honeywell MesoValve™ or Hoerbiger PiezoValve™). This approach mayenable fast sample acquisition despite long sampling lines, and yetprovide a regulated, approximately 0.1 to 3 cm³/min flow for thedetector. The pump of the sensor may be arranged to draw sample gasthrough a filter in such a way as to provide both fast sampleacquisition and regulated flow through the phased heater sensor.

As a pump draws sample gas through the sensor, the gas may expand andthus increase its volume and linear velocity. The control circuit may bedesigned to compensate for this change in velocity to keep the heater“wave” in sync with the varying gas velocity in the sensor. Tocompensate for the change in sample gas volume as it is forced throughthe heater channels, its electronics may need to adjust either the flowcontrol and/or the heater “wave” speed to keep the internal gas flowvelocity in sync with the heater “wave”.

During a gas survey operation, the sensor's ability (like any otherslower gas chromatographs) may sense multiple trace constituents of airsuch as about 330 to 700 ppm of CO₂, about 1 to 2 ppm of CH₄ and about0.5 to 2.5 percent of H₂O. This may enable on-line calibration of theoutput elution times as well as checking of the presence of additionalpeaks such as ethane, possibly indicating a natural gas, propane orother gas pipeline leak. The ratio of sample gas constituent peakheights thus may reveal clues about the source of the trace gases, whichcould include car exhaust or gasoline vapors.

The sensor may have the sensitivity, speed, portability and low powerthat make the sensor especially well suited for safety-mandated periodicleak surveys of natural gas or propane gas along transmission ordistribution pipeline systems and other gas in chemical process plants.

The sensor may in its leak sensing application use some or all samplegas constituents (and their peak ratios) as calibration markers (elutiontime identifies the nature of the gas constituents) and/or as leaksource identifiers. If the presence alone of a certain peak such asmethane (which is present in mountain air at about one to two ppm) maynot be enough information to indicate that the source of thatconstituent is from swamp gas, a natural or pipeline gas or anotherfluid.

The sensor may be used as a portable device or installed at a fixedlocation. In contrast to comparable related art sensors, it may be morecompact than a portable flame ionization detector without requiring thebulkiness of hydrogen tanks, it may be faster and more sensitive thanhot-filament or metal oxide combustible gas sensors, and much faster,more compact and more power-thrifty than conventional and/or portablegas chromatographs.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a diagram of a sensor system.

FIG. 2 shows details of a micro gas apparatus;

FIG. 3 is a layout of an illustrative phased heater mechanism;

FIG. 4 is a length-wise sectional view of a thin-film heater elements ona strenghtened channel;

FIG. 5 is a length-wise sectional view of a second embodiment of thetwin-film heater elements on a strenghtened channel;

FIGS. 6 a, 6 b and 6 c show cross-section end views of differentembodiments of the twin-film heater element and single film element.

FIG. 7 is a graph illustrating heater temperature profiles, along withcorresponding concentration pulses produced at each heater element ofthe sensor apparatus;

FIG. 8 is a graph showing several heater elements to illustrate astep-wise build-up on an analyte concentration in a pre-concentrator;

FIG. 9 is a graph showing a concentration pulse that reaches about 100percent concentration level;

FIG. 10 is a table of known detection limits and selectivities forvarious elements;

FIG. 11 shows known state of the art chromatograms of a multielementtest mixture;

FIG. 12 is a graph of the relative intensity, discharge versus pressurefor a gas;

FIG. 13 shows sectional views of an array of light source and detector(MDD) pairs for gas sensing.

FIG. 14 is a graph of a spectral responsivity comparison between an MDDand a Si-photo diode;

FIG. 15 is an illustration of an integrated layout for the phased heaterarray structure that includes sensors, a concentrator and a separator;

FIG. 16 is a schematic of the logic heating element selection forconcentrator and separator portions of a sensor.

FIG. 17 shows a micro analyzer with a hyper pre-concentrator.

FIG. 18 is a graph of analyte concentration versus time and location ofanalyte.

FIG. 19 is a table of analyte masses and corresponding film length andconcentration.

FIG. 20 shows a table revealing a pressure drop through a channel of100×100 microns in cross section relative to a number of elements.

FIG. 21 shows a micro analyzer having a general gas chromatograph—gaschromatograph type two-dimensional structure.

FIGS. 22 and 23 show structures like that in FIG. 21 but havingdifferent configurations.

FIG. 24 shows a table of design and performance parameters of a dualmicro gas chromatograph system.

FIG. 25 is diagram of a high pressure liquid chromatograph.

FIG. 26 a reveals a micro-brick component of the high pressurechromatograph.

FIG. 26 b shows a capillary component of the high pressurechromatograph.

DESCRIPTION

Detection and analysis by sensor 15 of FIG. 1 may include detection,identification and quantification of fluid components. That may includea determination of the concentration of or parts-per-million of thefluid detected. Sensor 15 may be used to detect fluids in theenvironment. Also, sensor 15 may detect miniscule amounts of pollutantsin ambient environment of a conditioned or tested space. Sensor 15 mayindicate the health and the level of toxins-to-people in ambient air orexhaled air.

FIG. 1 reveals an illustrative diagram of a low-power sensor system 11.A sample fluid 25 from a process stream, an ambient space or volume 61may enter a conduit or tube 19 which is connected to an input 34 of asensor or micro gas apparatus 15. Fluid 25 may be processed by sensor15. Processed fluid 37 may exit output 36 of sensor 15 and be exhaustedto volume 61 or another volume, wherever designated, via a conduit ortube 39.

Sensor 15 results may be sent to microcontroller/processor 29 foranalysis, and immediate conclusions and results. This information may besent on to observer stations 31 for review and further analysis,evaluation, and decisions about the results found. Data and controlinformation may be sent from stations 31 to microcontroller/processor29. Data and information may be sent and received via the wirelessmedium by a transmitter/receiver 33 at sensor 11 and at stations 31. Orthe data and information may be sent and received via wire or opticallines of communication by a modem 35 at monitor 11 and station 31. Thedata and information may be sent to a SCADA (supervisory control anddata acquisition) system. These systems may be used in industry(processing, manufacturing, services, health, and so on) to detectcertain gases and provide information relating to the detection toremote recipients.

Microcontroller or processor 29 may send various signals to analyzer 15for control, adjustment, calibration or other purposes. Also,microcontroller/processor 29 may be programmed to provide a prognosis ofthe environment based on detection results. The analysis calculations,results or other information may be sent to modem 35 for conversion intosignals to be sent to a station 31 via lines, fiber or other like media.Also, such output to modem 35 may be instead or simultaneously sent totransmitter 33 for wireless transmission to a station 31, together withinformation on the actual location of the detection obtained, e.g., viaGPS, especially if it is being used as a portable device. Also, stations31 may send various signals to modem 35 and receiver 33, which may bepassed on to microcontroller or processor 29 for control, adjustment,calibration or other purposes.

In FIG. 1, space 61 may be open or closed. Sensor system 11 may have ahook-up that is useable in a closed space 61 such as an aircraft-cabin,machinery room, factory, or some place in another environment. Or it maybe useable in an open space 61 of the earth's environment. The end ofinput tube or pipe 19 may be in open space 61 and exhaust of exit tube37 may be placed at a distance somewhat removed from a closed space 61.System 11 for space 61 may itself be within space 61 except that tube 39may exit into space 61, especially downstream in case space 61 is aprocess stream.

FIG. 2 reveals certain details of micro gas apparatus 15. Furtherdetails and variants of it are described below in conjunction withsubsequent figures. Sample stream 25 may enter input port 34 from pipeor tube 19. There may be a particle filter 43 for removing dirt andother particles from the stream of fluid 25 that is to enter apparatus15. This removal is for the protection of the apparatus and thefiltering should not reduce the apparatus' ability to accurately analyzethe composition of fluid 25. Dirty fluid (with suspended solid or liquidnon-volatile particles) might impair proper sensor function. A portion45 of fluid 25 may flow through the first leg of a differentialthermal-conductivity detector (TCD, or chemi-sensor (CRD), orphoto-ionization sensor/detector (PID), or other device) 127 and aportion 47 of fluid 25 flows through tube 49 to a pump 51. By placing a“T” tube immediately adjacent to the inlet 45, sampling with minimaltime delay may be achieved because of the relatively higher flow 47 tohelp shorten the filter purge time. Pump 51 may cause fluid 47 to flowfrom the output of particle filter 43 through tube 49 and exit from pump51. Pump 53 may effect a flow of fluid 45 through the sensor via tube57. Pump 51 may now provide suction capacity of 10–300 cm3/min at lessthan 1 psi (˜7 kPa) pressure drop (Δp) and low-flow-capacity pump 53 mayprovide 0.1–3 cm3/min at up to a Δp of 10 psi (˜70 kPa)). There may beadditional or fewer pumps, and various tube or plumbing arrangements orconfigurations for system 15 in FIG. 2. Data from detectors 127 and 128may be sent to control 130, which in turn may relay data tomicrocontroller and/or processor 29 for processing. Resultantinformation may be sent to station 31.

Pumps 51 and 53 may be very thrifty and efficient configurationsimplemented for pulling in a sample of the fluid being checked fordetection of possible gas from somewhere. Low-power electronics having asleep mode when not in use may be utilized. The use of this particularlythrifty but adequately functional pump 51 and 53, which may run onlyabout or less than 1–10 seconds before the start of a concentratorand/or measurement cycle of analyzer system 11, and the use of low-powerelectronics for control 130 and/or microcontroller/processor 29 (whichmay use a sleep mode when not in use) might result in about a two timesreduction in usage of such power.

FIG. 3 is a schematic diagram of part of the sensor apparatus 10, 15,representing a portion of concentrator 124 or separator 126 in FIG. 2.The sensor apparatus may include a substrate 12 and a controller 130.Controller 130 may or may not be incorporated into substrate 12.Substrate 12 may have a number of thin film heater elements 20, 22, 24,and 26 positioned thereon. While only four heater elements are shown,any number of heater elements may be provided, for instance, between twoand one thousand, but typically in the 20–100 range. Heater elements 20,22, 24, and 26 may be fabricated of any suitable electrical conductor,stable metal, or alloy film, such as a nickel-iron alloy sometimesreferred to as permalloy having a composition of eighty percent nickeland twenty percent iron; platinum, platinum silicide and polysilicon.Heater elements 20, 22, 24, and 26 may be provided on a thin,low-thermal mass, low-in-plane thermal conduction, support member 30, asshown in FIGS. 4 and 5. Support member or membrane 30 may be made fromSi₃N₄ or other appropriate or like material. The heater elements may bemade from Pt or other appropriate or like material.

Substrate 12 may have a well-defined single-channel phased heatermechanism 41 having a channel 32 for receiving the sample fluid stream45, as shown in FIG. 4. FIG. 5 reveals a double-channel phased heaterdesign 41 having channels 31 and 32. Substrate 12 and portion or wafer65 may have defined channels 31 and 32 for receiving a streaming samplefluid 45. The channels may be fabricated by selectively etching siliconchannel wafer substrate 12 beneath support member 30 and wafer orportion 65 above the support member. The channels may include an entryport 34 and an exhaust port 36.

The sensor apparatus may also include a number of interactive elementsinside channels 31 and 32 so that they are exposed to the streamingsample fluid 45. Each of the interactive elements may be positionedadjacent, i.e., for closest possible contact, to a corresponding heaterelement. For example, in FIG. 4, interactive elements 40, 42, 44, and 46may be provided on the lower surface of support member 30 in channel 32,and be adjacent to heater elements 20, 22, 24, and 26, respectively. InFIG. 5, additional interactive elements 140, 142, 144, and 146 may beprovided on the upper surface of support member 30 in second channel 31,and also adjacent to heater elements 20, 22, 24, and 26, respectively.There may be other channels with additional interactive film elementswhich are not shown in the present illustrative example. The interactiveelements may be formed from any number of films commonly used in liquidor gas chromatography, such as silica gel, polymethylsiloxane,polydimethylsiloxane, polyethyleneglycol, porous silica, Nanoglass™,active carbon, and other polymeric substances. Furthermore, the aboveinteractive substances may be modified by suitable dopants to achievevarying degrees of polarity and/or hydrophobicity, to achieve optimaladsorption and/or separation of targeted analytes.

FIG. 6 a shows a cross-section end view of two-channel phased heatermechanism 41. The top and bottom perspectives or orientations ofportions in FIGS. 6 a, 6 b and 6 c may not necessarily appear to be thesame. An end view of a single channel phased heater mechanism 41 mayincorporate the support member 30 and substrate 12 and the items betweenthem, in FIGS. 6 b and 6 c. FIG. 6 b shows a version of the phasedheater mechanism 41 having an exposed 1 micron membrane. Shown in FIG. 6b is open space 392. FIG. 6 c shows a ruggedized, low power versionhaving a small closed space 394. Support member 30 may be attached totop structure 65. Anchors 67 may hold support member 30 in placerelative to channel 31. Fewer anchor 67 points minimize heat conductionlosses from support 30 to other portions of structure 41. There may be aheater membrane that has a small number anchor points for little heatconduction from the heater elements. In contrast to a normal anchoringscheme, the present example may have a reduction of anchor points toresult in the saving about 1.5 times of the remaining heater elementinput power.

The heater elements of a phased heater array may be coated with anadsorber material on both surfaces, i.e., top and bottom sides, for lesspower dissipation and more efficient heating of the incoming detectedgas. The heater elements may have small widths for reduced powerdissipation.

Interactive film elements may be formed by passing a stream of materialcarrying the desired sorbent material through channel 32 ofsingle-channel heating mechanism 41. This may provide an interactivelayer throughout the channel. If separate interactive elements 40, 42,44, 46 are desired, the coating may be spin-coated onto substrate 30attached to the bottom wafer 12, before attaching the top wafer 65 inFIG. 6 a, and then selectively “developed” by either using standardphotoresist masking and patterning methods or by providing a temperaturechange to the coating, via heater elements 20, 22, 24 and 26.

The surfaces of inside channel of the heater array, except thosesurfaces intentionally by design coated with an adsorber material, maybe coated with a non-adsorbing, thermal insulating layer. The thicknessof the adsorber coating or film may be reduced thereby decreasing thetime needed for adsorption and desorption. As in FIG. 6 a, coating 69 ofa non-adsorbing, thermal insulating material may be applied to theinside walls of channel 31 in the single-channel heater 41, and the wallof channels 31 and 32 in the dual-channel heater mechanism 41, exceptwhere there is adsorber coated surfaces, by design, such as theinteractive elements. Coating 69 may reduce the needed heater elementpower by about 1.5 times. The material should have thermal conductionthat is substantially less than the material used in the channel walls.The latter may be silicon. Alternative materials for coating 69 mayinclude SiO₂ or other metal oxides. Coating 69 may reduce power used forthe heater elements in support 30. A minimizing or reduction of the size(width, length and thickness) of the heater element membranes as well asthe adsorber film, while retaining a reasonable ratio ofmobile/stationary phase volume, may result in about a four times powerreduction. The minimized or reduced adsorber film thickness may reducethe time needed for adsorption-desorption and save about 1.5 times inenergy needed per fluid analysis.

Heater elements 20, 22, 24 and 26 may be GC-film-coated on both the topand bottom sides so that the width and power dissipation of the heaterelement surface by about two times. The fabrication of these heaterelements involves two coating steps, with the second step requiringwafer-to-wafer bonding and coating after protecting the first coatinside the second wafer and dissolving the first wafer.

Another approach achieving the desired ruggedness (i.e. not expose athin membrane 20, 22, 24, . . . to the exterior environment) but withoutthe need to coat these both top and bottom, is to coat only the top andreduce the bottom channel 32 to a small height, see FIG. 6 a, so thatthe volumetric ratio (air/film) is of a value of less than 500.

The micro gas analyzer may have heater elements 40, 42, . . . , 44, 46and 140, 142, . . . , 144, 146 fabricated via repeated, sequentiallyspin-coated (or other deposition means) steps, so that a pre-arrangedpattern of concentrator and separator elements are coated with differentadsorber materials A, B, C, . . . (known in GC literature as stationaryphases), so that not only can the ratio of concentrator/separatorelements be chosen, but also which of those coated with A, B, C and soforth may be chosen (and at what desorption temperature) to contributeto the concentration process and electronically be injected into theseparator, where again a choice of element temperature ramping rates maybe chosen for the A's to be different for the B, C, . . . elements; andfurthermore adding versatility to this system in such a way that afterseparating the gases from the group of “A”-elements; another set ofgases may be separated from the group of “B” elements, and so forth. Theratio of concentrator to separator heater elements may be set or changedby a ratio control mechanism 490 connected to controller 130.

Controller 130 may be electrically connected to each of the heaterelements 20, 22, 24, 26, and detector 50 as shown in FIG. 3. Controller130 may energize heater elements 20, 22, 24, and 26 in a time phasedsequence (see bottom of FIG. 7) such that each of the correspondinginteractive elements 40, 42, 44, and 46 become heated and desorbselected constituents into a streaming sample fluid 45 at about the timewhen an upstream concentration pulse, produced by one or more upstreaminteractive elements, reaches the interactive element. Any number ofinteractive elements may be used to achieve the desired concentration ofconstituent gases in the concentration pulse. The resultingconcentration pulse may be provided to detector 50, 128, for detectionand analysis. Detector 50, 127, or 128 (FIGS. 2 and 3) may be athermal-conductivity detector, discharge ionization detector, CRD, PID,MDD, or any other type of detector such as that typically used in gas orfluid chromatography.

FIG. 7 is a graph showing illustrative relative heater temperatures,along with corresponding concentration pulses produced at each heaterelement. As indicated above, controller 130 may energize heater elements20, 22, 24, and 26 in a time phased sequence with voltage signals 71.Illustrative time phased heater relative temperatures for heaterelements 20, 22, 24, and 26 are shown by temperature profiles or lines60, 62, 64, and 66, respectively.

In the example shown, controller 130 (FIG. 3) may first energize firstheater element 20 to increase its temperature as shown at line 60 ofFIG. 7. Since first heater element 20 is thermally coupled to firstinteractive element 40 (FIGS. 4 and 5), the first interactive elementdesorbs selected constituents into the streaming sample fluid 45 toproduce a first concentration pulse 70 (FIG. 7) at the detector 128 or50, if no other heater elements were to be pulsed. The streaming samplefluid 45 carries the first concentration pulse 70 downstream towardsecond heater element 22, as shown by arrow 72.

Controller 130 may next energize second heater element 22 to increaseits temperature as shown at line 62, starting at or before the energypulse on element 20 has been stopped. Since second heater element 22 isthermally coupled to second interactive element 42, the secondinteractive element also desorbs selected constituents into streamingsample fluid 45 to produce a second concentration pulse. Controller 130may energize second heater element 22 such that the second concentrationpulse substantially overlaps first concentration pulse 70 to produce ahigher concentration pulse 74, as shown in FIG. 7. The streaming samplefluid 45 carries larger concentration pulse 74 downstream toward thirdheater element 24, as shown by arrow 76.

Controller 130 may then energize third heater element 24 to increase itstemperature as shown at line 64 in FIG. 7. Since third heater element 24is thermally coupled to third interactive element 44, third interactiveelement 44 may desorb selected constituents into the streaming samplefluid to produce a third concentration pulse. Controller 130 mayenergize third heater element 24 such that the third concentration pulsesubstantially overlaps larger concentration pulse 74 provided by firstand second heater elements 20 and 22 to produce an even largerconcentration pulse 78. The streaming sample fluid 45 carries thislarger concentration pulse 78 downstream toward an “Nth” heater element26, as shown by arrow 80.

Controller 130 may then energize “N-th” heater element 26 to increaseits temperature as shown at line 66. Since “N-th” heater element 26 isthermally coupled to an “N-th” interactive element 46, “N-th”interactive element 46 may desorb selected constituents into streamingsample fluid 45 to produce an “N-th” concentration pulse. Controller 130may energize “N-th” heater element 26 such that the “N-th” concentrationpulse substantially overlaps larger concentration pulse 78 provided bythe previous N-1 interactive elements. The streaming sample fluidcarries “N-th” concentration pulse 82 to either a separator 126 or adetector 50 or 128, as described below.

As indicated above, heater elements 20, 22, 24, and 26 may have a commonlength. As such, controller 130 can achieve equal temperatures of theheater elements by providing an equal voltage, current, or power pulseto each heater element. The voltage, current, or power pulse may haveany desired shape including a triangular shape, a square shape, a bellshape, or any other shape. An approximately square shaped voltage,current, or power pulse is used to achieve temperature profiles 60, 62,64, and 66 shown in FIG. 7. The temperature profiles look like that, andnote that the desorbed species are generated with a small time delay,relative to the voltage pulses.

FIG. 8 is a graph showing a number of heater elements to illustrate,first, how the concentration increases stepwise as the desorption ofsubsequent elements is appropriately synchronized with the streamingsample fluid velocity and, second, how the lengths of individualelements are matched to the expected increased rate of mass diffusivityflux as the concentration levels and gradients increase. It should bepointed out here that prior to the elements shown in FIG. 8, the analyteconcentration may have been already magnified by a factor, F, by virtueof pulsing an initial element with a length F-times longer than the oneshown as element 100 (H1) or, alternatively, by simultaneously pulsingelements 1, 2, . . . , F and collecting all the desorbed analyte withthe still cool element 100 (H1), before pulsing it. It is recognizedthat each of the concentration pulses may tend to decrease in amplitudeand increase in length when traveling down channel 32 due to diffusion.To accommodate this increased length, it is contemplated that the lengthof each successive heater element may be increased along the streamingsample fluid. For example, a second heater element 102 may have a lengthW₂ that is larger than a length W₁ of a first heater element 100.Likewise, a third heater element 104 may have a length W₃ that is largerthan length W₂ of second heater element 102. Thus, it is contemplatedthat the length of each heater element 100, 102, and 104 may beincreased, relative to the adjacent upstream heater element, by anamount that corresponds to the expected increased length of theconcentration pulse of the upstream heater elements due to diffusion.However, in some cases in which the target analyte concentrations arevery small or the adsorbing film capacities are very large, it may bepossible and advantageous to significantly decrease the length ofsubsequent or last heater elements in order to achieve maximum focusingperformance of the concentrator function, which is based on minimizingthe film volume into which we can adsorb a given quantity of analyte(s)from a given volume of sample gas pumped (pump 51 in FIG. 2) through theconcentrator during a given time, and thus increase the analyte(s)concentration by the same ratio of sample volume/film volume (of thelast heater element).

To simplify the control of the heater elements, the length of eachsuccessive heater element may be kept constant to produce the sameoverall heater resistance between heater elements, thereby allowingequal voltage, current, or power pulses to be used to produce similartemperature profiles. Alternatively, the heater elements may havedifferent lengths, and the controller may provide different voltage,current, or power pulse amplitudes to the heater element to produce asimilar temperature profile.

FIG. 9 is a graph showing a concentration pulse 110 that achieves a 100percent concentration level. It is recognized that even thoughconcentration pulse 110 has achieved a maximum concentration level, suchas 100 percent, the concentration of the corresponding constituent canstill be determined. To do so, detector 50, 128, 164 may detect theconcentration pulse 110, and controller 130 may integrate the outputsignal of the detector over time to determine the concentration of thecorresponding constituent in the original sample of stream 45.

In “GC peak identification”, it is desired to associate unequivocally achemical compound with each gas peak exiting from a gas chromatograph(GC), which is a tool to achieve such separations of individualconstituents from each other. There are several approaches foridentifying components of a gas. In a GC-MS combination, each GC-peak isanalyzed for its mass, while processing the molecular fragmentsresulting from the required ionization process at the MS inlet. In aGC-GC combination, different separation column materials are used in thefirst and second GC, in order to add information to the analysis record,which may help with compound identification. In a GC-AED combination, amicrowave-powered gas discharge may generate tell-tale optical spectralemission lines (atoms) and bands (molecules) to help identify the gas ofthe GC-peak in the gas discharge plasma. In the GC-MDD or GC-GC-MDDconfigurations, the micro discharge device (MDD) may emit spectra of theanalyte peaks as they elute from the GC or GC-GC, and reveal molecularand atomic structure and thus identification of the analyte peaks.

An example of how the selective wavelength channels of an AED canidentify the atomic makeup of a compound separated by GC is illustratedin FIG. 11, which shows separate channels for C, H, N, 0, S, Cl, Br, P,D, Si and F atomic emissions, with a corresponding list of channels inthe table of known detection limits and selectivities in FIG. 10. FIG.11 shows known state-of-the-art chromatograms of a multielement testmixture with various peaks that may indicate the element and itsapproximate amount. Peak 301 indicates 2.5 ng of 4-fluoroanisole; peak302 indicates 2.6 ng of 1-bromohexane; peak 303 indicates 2.1 ng oftetraethylorthosilicate; peak 304 indicates 1.9 ng ofn-perdeuterodecane; peak 305 indicates 2.7 ng of nitrobenzene; peak 306indicates 2.4 ng of triethyl phosphate; peak 307 indicates 2.1tert-butyl disulfide; peak 308 indicates 3.3 ng of1,2,4-trichlorobenzene; peak 309 indicates 170 ng of n-dodecane; peak310 indicates 17 ng of n-tridecane; and peak 311 indicates 5.1 ng ofn-tetradecane. For such chromatograms, the GC conditions may include acolumn flow of 3.3 mL/min, a split ratio of 36:1, and an oven programfrom 60 degrees to 180 degrees Centigrade (C) at 30 degrees C/min. Partof a UV spectrum of neutral and ionized emitters of Ne, generated withlow-power microdischarges are shown in FIG. 12. The graph of FIG. 12 isfrom work done by the University of Illinois. Also shown in this figureis that the spectral species change in intensity as the “Ne” pressurechanges. The optical output may depend on several parameters such asdischarge cavity geometry, applied voltage and pressure. Molecular bandsare emitted and may even be used for “NO” measurements of such gases asin the hot exhaust of jet engines.

One may obtain useful gas composition information by feeding anenvironmental gas sample to microdischarge devices. In a first approach,one may use one microgas discharge device, the operating parameters(voltage, pressure, flow . . . and possibly the geometry) of which maybe changed to yield variations in the output emission spectrum such thatafter evaluation and processing of such emission data, information onthe type and concentration of the gas sample constituents may be made.In a second approach, one may use several micro-gas discharge devices,whereby the operating parameters of each may be changed, for emissionoutput evaluation as in the first approach, and may obtain betterresults via a statistical analysis. The third approach may be the sameas the first one, except that each micro-discharge may be only operatedat one condition, but set to be different from that of the set-point ofthe other microdischarges.

FIG. 13 represents the third approach, whereby the gas sample may passserially from one type of discharge to the next, and the assumption maybe that the nature of the gas sample does not change during thisprocess. The figure shows an array 350 of light source—detector pairsfor gas composition sensing in a gas 45 stream at various pressures andvoltages. The different voltages, +V1, +V2 . . . and pressures P1 and P2may be marked as such. The plasma of the micro discharges 352 from thelight source block 351 are indicated by the ellipsoids between the (+)and (−) electrodes. Opposing source block 351 is a detector block 353having micro gas discharge devices operating as detectors 354 of thelight from the source discharges 352. There may be filters situated ondetectors 354. The filters may be different and selected for detectionand analysis of particular groups of gases. The various lines ofemission of the gases from the micro discharges may be detected andidentified for determining the components of a detected gas. Array 350may be connected to controller 130. A processor may be utilized in thecontrol of the micro discharges and the detection of the effects of thedischarges in the flow of gas 45 through array 350.

Light source block 351 may be made from silicon. Situated on block 351may be a wall-like structure 355 of Si₃N₄ or Pyrex™, forming a channelfor containing the flow of gas 45 through device 350. On top ofstructure 355 may be a conductive layer of Pt or Cu material 356. On thePt material is a layer 357 of Si₃N₄ that may extend over the flowchannel. On top of layer 357 may be a layer 358 of Pt and a layer 359 ofSi₃N₄ as a wall for forming a channel for detectors 354. The fourthapproach may be like the third approach except for the feeding the gassample to each discharge in a parallel rather than serial fashion.

A fifth approach may be the same as the fourth or third approach, exceptthat the gas sample may have undergone a separation process as provided,e.g., by a conventional GC. A sixth approach may be the same as thefifth approach, except that prior to the separation process, the sampleanalytes of interest may be first concentrated by a conventionalpre-concentration step.

The seventh approach may be the same as the sixth approach, except thatprior to the separation process, the sample analytes of interest mayhave been previously concentrated by a multi-stage pre-concentrationprocess and then electronically injected into the separator as offeredby the phased heater array sensor.

In the sixth and seventh approaches with reference to FIG. 2, the ideais to feed individual gas-analyte peaks eluting from the GC column orthe phased heater array sensor separator channel to each dischargedevice in the shown array of discharges.

Gas flow may be in series as shown in FIG. 13. Or it may be in parallelwhich may be necessary for an optimal peak identification, whereby (forthe sake of minimizing total analysis time) each discharge cell mayoperate at a fixed condition of applied voltage, gas pressure(determined by the vacuum or suction pump at the exit of the array,e.g., by a Mesopump™). In FIG. 13, only two pressures may be indicatedby way of example, as easily achieved by a flow restriction between the4^(th) and 5^(th) discharge element. Several changes in the dischargeparameter such as flow rate, temperature (via local micro-heaters) orgeometry (hollow-cathode or flat-plate discharge, besides simple changesin the identification of cell) are not shown, but may be likewiseimplemented.

Due to their typically small size (10–100 μm), these sensors may notappear to use much real estate and may be included in block 128 of FIG.2.

Sensor 15 may have a flow sensor 125 situated between concentrator 124and separator 126, a thermal-conductivity detector at the input ofconcentrator 124. It may have a thermal-conductivity detector betweenconcentrator 124 and separator 126. There may be a thermal-conductivitydetector at the output of discharge mechanism 350. Sensor 15 may includevarious combinations of some of the noted components in variouslocations in the sensor 128 of FIG. 2, depending upon the desiredapplication. The drawing of sensor 15 in FIG. 2 is an illustrativeexample of the sensor. Sensor 15 may have other configurations notillustrated in this figure.

The gas micro-discharge cells may offer attractive features, which maysignificantly enhance the usefulness, versatility and value of thephased heater array sensor. Examples of the features include: 1) lowpower capability—each discharge operates at 700–900 Torr (0.92–1.18 bar)with as little as 120 V DC, at 10 μm, which may amount to 1.2 mW thatappears to be a minimal power not even achieved by microTDCs; 2) ease ofbuilding along with a compactness (50×50 μm), shown the insert of FIG.12; 3) the operability of micro-discharges as photo detectors which maybe shown by the spectral responsivity comparison between a 100 μmmicrodischarge and an Si APD in FIG. 14 (which is a graph from work bythe University of Illinois), which no other light sources such as 100-Wmicrowave driven AEDs (requiring water cooling) are known to do; 4) theintegratability and wafer level assembly of the discharge source andphotodiodes with a phased heater array structure, without having toresort to Si-doping to manufacture monolithic Si-photodiodes; and 5) theadded dimensionality (i.e., selectivity) by varying discharge parametersas noted above.

The present invention may have gas composition sensing capabilities viamicro-discharge having: 1) a combination of phased heater array sensorwith micro gas discharge devices; 2) the combination of 1), whereby oneset or array of gas discharge devices may provide the spectral emissionand another, complementary set (with or without narrow-band band-passfilters or micro spectrometer) may provide the light detection function;3) the combination of 2) with appropriate permutations of designsdescribed above under the first through seventh approaches; and 4) theflexibility to program heatable elements as additional pre-concentratoror additional separator elements of the phased heater array structure,as needed for a specific analysis, to achieve optimal preconcentrationor separation performance.

The present phased heater array sensor-microdischarge detectorcombination over previously proposed micro gas analyzers may providesensitivity, speed, portability and low power of the phased heater arraysensor, combined with the selectivity, “peak-identification” capability,low-power, light source and detection capability, integratability,simplicity and compactness contributed by micro gas discharge devices,which no other microanalyzers have been known to achieve.

FIG. 15 illustrates the integration of sensors, pre-concentrator and/orconcentrator 124 and separator 126 of micro gas apparatus 15 (i.e., thephased heater array structure) on a single chip 401 which would bemounted and connected on a circuit board that also connects with otherchips as well. One such other chip may hold FET switches, shiftregisters and logic. The 401 chip may reside on a daughter board. The401 chip and the main circuit board were originally connected by about110 wires. However, after the integration of all of the switches ontothe separate chip on the daughter board, the number of printed circuitboard routing leads and connector pins was reduced to about 10 (i.e.,for differential temperature compensation, flow sensor, switch clock,logic, power and ground). The FET switches, shift registers and controllogic located on a separate IC may be connected to the phased heaterarray structure chip via wire-bonds or solder-bumps. With the new logicof the FETs, a user of sensor system 15 may select the fraction of totalheatable elements for operating as preconcentrators versus separators.

FIG. 16 is a schematic of an illustrative example 402 of control logicfor sensor system 11. Circuit 410 may be an instance of a logic cell inan array. It may contain D flip-flops 403, R-S flip-flops 404, AND gates405 and 415, OR gates 406, FETs 407 and an inverter 408, plus additionalcircuitry as needed. A clock line 411 may be connected to a clock inputof D flip-flop 403. A separator enable line 413 may be connected to afirst input of AND gate 405. A data-in line 412 may be connected to a Dinput of flip-flop 403. A reset line 414 may be connected to an S inputof flip-flop 404 and a reset input of flip-flop 403. A Q output offlip-flop 404 may be connected to a second input of AND gate 405. A Qoutput of flip-flop 403 may be connected to an R input of flip-flop 404and to a first input of AND gate 415. Separator enable line 413 may beconnected to an input of inverter 408. An output of inverter 408 may beconnected to a second input of AND gate 415. Outputs of AND gates 415and 405 may be connected to first and second inputs, respectively, of ORgate 406. An output of OR gate 406 may be connected to a gate of FET407. The other terminals of FET 407 may be connected to a FET commonline 416 and a FET output terminal 417, respectfully. The far rightlogic cell may have a Q output of flip-flop 403 connected to a data outline 418.

This logic may allow the user to pre-select the number ofpre-concentrator elements that the circuit will pulse and heat up,before pausing and then ramping up the temperature on all of theremaining heater elements, which then may function as part of thesegmented separator. There is an additional dimension of flexibilitywhich may allow for the depositing of different materials on any of thephased heater array sensor elements of chip 401 chip via suitablemasking, so that preferential preconcentration, filtering ofinterference and cascaded separation may be enabled.

FIG. 16 further illustrates how up to 50 FET switches may be controlledby on-chip logic, each having an on resistance at or below 0.5 ohms andbe able to switch about 12 volt potentials. The on-chip logic mayoperate in two modes, that is, the concentrator or 1^(st) mode and theseparator or 2^(nd) mode, the respective mode being determined by acontrol line bit. The 1^(st) mode may involve a shift register which,after a reset, sequentially turns on a low resistance FET, and disablesa flip-flop associated with that same FET. At the next clock cycle, thefirst FET turns off, and the next FET turns on and its associatedflip-flop is disabled. This sequence may be repeated until some externaldrive electronics turns off the clock and enables the 2^(nd) operatingmode. Once the second mode is enabled, all of the FETs where theflip-flop has not been disabled may turn on simultaneously. This 2^(nd)mode may stay on until the reset has been triggered and the flip-flopsare reset, the FETs are turned off and the process can be repeated.

Two chips may be used in series to bond to the (up to 50) the phasedheater array sensor chip pads on each of its sides, such that thesequential switching will go from the first chip to the second chip. Itmay be necessary for the signal from the last switch on the first chipto trigger the first switch on the second chip. It is possible that themode switch from sequential addressing of the remaining FETs in parallelmay happen sometime before or after the switching has moved to thesecond chip.

One may introduce adsorber coating diversity into the phased heaterarray sensor heater elements, such as by alternating individual elementsor groups of elements in either or both preconcentrator or theseparator, with more than one adsorber material, and adjusting the logicprogram for the switches as in FIG. 16 or to favor (in terms of maximumapplied voltage or temperature) certain types of coatings in thepreconcentrator and equally or differently in the separator, to achievethe desired analyte preconcentrating, analyte filtering and analysisresults which may be the analysis of selected group preconcentratorpulses or cascaded (in time) preconcentrator analyte pulses.

The user may be enabled with great flexibility to adjust the phasedheater array sensor operation and performance to the varying needsimposed by the analysis problem: He can select the number or fraction oftotal heater array elements to function as pre-concentrators vs.separators, thus varying the concentration of the analyte relative tothe separation, i.e., resolution and selectivity of the analytecomponents, while retaining the ability to design and fabricatelow-power, optimally temperature-controlled heater elements, thatfeature structural integrity, optimal focusing features, analyteselectivity/filtering, and smart integration of preconcentration,separation, flow control and detection technology, such as TC andmicro-plasma-discharge sensors. One may integrate the CMOS driveelectronics with the phased heater array sensor flow-channel chip.

In important gas analysis situations, such as when health-threateningtoxins, chemical agents or process emissions need to be identified withlittle uncertainty (low probability for false positives) and quantified,conventional detectors and even spectrometers (MS, GC, or optical)cannot provide the desired low level of false positives probability,P_(fp).

Combined analyzers such as in GC-MS and GC-GC systems may approach thedesired low P_(fp) values, but are typically not-portable desk-topsystems, because of two sets of complex and bulky injection systems,bulky MS pumping systems and large amounts of energy needed for eachanalysis. Most importantly, the false positives probability rapidlyincreases if desktop or portable systems cannot provide the neededsensitivity, even if the separation capability is excellent.

A solution is embodied in a micro analyzer 500 shown in FIG. 17, whichmay combine the selectivity provided by the μGC-μGC-like configurationif needed, that is, if not a simple micro gas chromatograph (μGC) woulddo, as well as the sensitivity afforded by the multi-level, multi-stagepre-concentration. In this configuration, micro analyzer 500 may stillretain its (palm-top to cubic-inch type) compactness, 3-second analysis,ppb sensitivity, flexibility, smartness, integrated structure, low-powerand low cost features. Another solution may be embodied in a microanalyzer 600 of FIG. 21.

Micro analyzer 500 may take in a sample stream of fluid 530 through aninput to a filter 527. From filter 527, fluid 530 may go through a microdetector (μD) 531 on into a 1^(st)-level pre-concentrator 526 havingparallel channels 527. Fluid 530 may be drawn through channels 527 bypump 521 or by pump 522 through the main portion of micro analyzer 500.Pumps 521 and 522 may operate simultaneously or according to individualschedules. A portion of fluid 530 may go through concentrator 523 and onthrough flow sensor 532. Concentrator 523 may have an about 100 microninside diameter. From flow sensor 532, fluid 530 may go throughseparator 524, micro detector 533, separator 525 and micro detector 534.Separators 524 and 525 may have inside diameters of about 140 micronsand 70 microns, respectively. Fluid 530 may flow on to pump 522. Fluid530 exiting from pumps 521 and 522 may be returned to the place that thefluid was initially drawn or to another place. Each of micro detectors531, 533 and 534 may be a TCD, MDD, PID, CRD, MS or another kind ofdetector. Analyzer 500 may have more or fewer detectors than thoseshown. It may also have flow orifices, such as orifices 541 and 542 atthe outlets of micro detectors 533 and 534, respectively. Analyzer 500may also have valves and other components. A control device 535 or microcontroller or processor may be connected to pumps 521 and 522, detectors531, 533 and 534, sensor 532, concentrator 523, separators 524 and 525,and other components as necessary to adequately control and coordinatethe operation of analyzer 500, which may be similar to that of a microfluid analyzer described in the present description.

A feature of micro analyzer 500 may relate to the introduction ofadditional pre-concentration dimensions. Each of these supplies anenhanced analyte concentration to the subsequent pre-concentratoroperation, as depicted schematically in FIG. 17. This is different frompreviously proposed and built single-level, multi-stagepre-concentrators (PC). In the multi-level PC system, the analyteconcentration achieved in the 1^(st)-level PC and presented foradsorption to the next or last-level (multi-element and multi-stage)pre-concentrator is already enhanced by the 1^(st)-levelpre-concentrator, and this previous pre-concentrator needs to be largeenough to be able to release analyte for the time period needed forabout full operation of the 2^(nd)-level or last pre-concentrator.

Assuming that the volumetric ratios of mobile phase over stationaryphase and the ratio of partition functions at adsorption and desorptiontemperatures is such that G=100-fold concentration gains can be achievedfor a hypothetical analyte, then the timing of increasing concentrationlevels is as indicated by the sequence of numbers 511, 512, 513, 514,515 and 516 in FIG. 18 as follows (it helps to remember that for gasdiffusion to evenly re-distribute removed or desorbed gas in a squarecross section channel of side, d=0.01 cm only takes a time ofΔt=d²/(2D)=0.01²/2/0.1=0.0005 seconds).

The multi-level PC operation may be described as going through asequence of steps: 1) Adsorption time, z_(a). Analyte of mol fractionX=1 ppt flows with the sample gas at v=110 cm/s, for sufficient time,z_(a), to equilibrate with the stationary phase: z_(a)=N₁GL/v, whereN₁=number of adsorbing elements, L=length of adsorbing film element inthe flow direction. For N₁=500 and L=0.5 cm one may getz=500×100×0.5/110=227 seconds. Note that z_(a) is independent of X,provided X is small relative to 1 even after all preconcentration stepsare completed. (For chips with N₁=50, the time would be 22.7 seconds,for chips with L=0.1, this time could be 4.3 seconds. Increasing thesample gas flow velocity would decrease this time, but increasing thefilm thickness would increase that time).

2) Saturation. At the end of the time, z=z_(a), the first-stage adsorberis largely saturated (one may ignore here for clarity's sake, theexponential nature of the diffusional mass transfer from the sample gasto the stationary film), while the sample gas continues to flow withanalyte concentration, x, as indicated by the dashed line. In FIG. 18,this is indicated by concentration regions 511 and 512 for the gas andstationary phases, respectively.

3) 1st-Level Desorption Start. At any time z≧z_(a), e.g., z=z_(o), onemay rapidly (within 1 ms) heat all N₁ elements, which then fill thesample gas channel with a 100× higher concentration, i.e., x=100 ppt(see region 513 in FIG. 18). As the “plug” of this 100-fold enrichedsample gas enters the first element of the next level PC, N₂, it willtry to equilibrate and saturate the next set of N₁/G adsorber elementsof N₂ with a 100× higher analyte concentration (region 514 in FIG. 18)than in the previous region 512.

4) 2nd-Level Adsorption Time Period. One may only have available afinite time and finite plug or column of gas moving at a velocity, v, todo this, before unconcentrated sample gas purges the concentratedanalyte out of region 514 in FIG. 18. The available timez≈N₁L/v=z_(a)/G, or 2.27 seconds, for the above but arbitrary examplewith N₁=500, L=0.5 cm and v=110 cm/s.

5) 2nd-Level Desorption Time Start. The second desorption should startno later than at z=z_(o)+z_(a)/G, by heating only the first of the N₂elements, for a time Δz=L/v, which may be between 1 and 5 ms (in theexample, Δz=4.5 ms). This may generate and raise the analyteconcentration in the channel (region 515 in FIG. 18) 10,000-fold,relative to the original x-value. When the time Δz has passed, thesecond element may be heated, and so on, until all N_(2=N) ₁/G elementshave been pulsed, and thus added their desorbed analyte to the passinggas. The time needed to do this may be Σ(Δz)=Δz·N₂=(N₁/G) (L/v)=z_(a)/G²or 227/10⁴=23 ms, for an arbitrary example with N₁=500, N₂=N₁/G=5, L=0.5cm and v=110 cm/s.

6) 2nd-Level Desorption Time Period. The final analyte concentrationexiting this pre-concentrator at region 516 in FIG. 18 may bex=x_(o)G²N₂=x_(o)N₁G=50,000, i.e., a 50,000-fold increase over thestarting analyte concentration in the sample gas. This may be a ˜10×higher pre-concentration gain than achieved when the source analyte wasadsorbed only once and concentrated with only one set of phasedelements.

The example with N₁=500 used above was entered as row A in the table ofFIG. 19. Rows B–E list additional examples with increasing number ofelements and correspondingly larger total concentration gains achieved.However, the pressure drop through a typical MEMS channel of 100×100 μmin cross section increases rapidly as we increase the number ofelements, as shown in the table of FIG. 20. For just N₁=50, v=100 cm/sand L=0.5 cm, one may get Δp=2.6 psid (˜18 kPa d), with air as the maincomponent in the sample gas. The Δp for N₁+N₂=505 or 1010-elementpre-concentrators may rapidly become impracticably large, even if eachelement is shortened to L=0.1 cm, as shown via the pressure drops andpeak power data computed and listed in FIG. 20, showing Δp values of 5.3and 10.6 psi (˜36.5 and 73.1 kPa), respectively. One way to alleviatethis high-pressure drop, which is especially undesirable for systems inwhich the sample is drawn through via a suction pump, is by setting upthe N₁ elements in two or more equal and parallel channels. For qparallel channels, the pressure drop may fall to Δp/q, without changingthe soaking time or the needed peak power, because desorption of all theparallel elements of N₁ needs to be occurring simultaneously, unlesseach channel is provided with suitable valving, so that they can bedesorbed sequentially. Preferably, the soaking time could be reduced bythis scheme of parallel channels, without valves, by using the two-pumps521 and 522, as illustrated in FIG. 17.

While both pumps 521 and 522 may draw sample gas during the soakingperiod, the flow through micro analyzer 500 may be unaffected due to thestronger vacuum of its pump 522, but may allow a 1st-levelpre-concentrator 526 to draw 10–100× larger flow rates with its pump 521and thus complete this soaking period in a 10–100× less time. After theend of the soaking period, one may stop pump 521 and let pump 522 drawsample gas through both concentrator 523 and separators 524 and 525 ofmicro analyzer 500 and added pre-concentrator 526 with parallel channels527.

Hyper pre-concentrator 526 concentrator 523 and concentrator 623 mayhave channels which include heater elements 20, 22, 24, 26 and so onwith interactive elements 40, 42, 44 and 46 and so on, and alternativelywith additional interactive elements 140, 142, 144, 146 and so on, as inFIGS. 3–5. Controller 535 and 635 may be electrically connected to eachof the heater elements 20, 22, 24, 26. Controller 535 and 635 mayenergize heater elements 20, 22, 24, and 26 in a time phased sequence(see bottom of FIG. 7) such that each of the corresponding interactiveelements 40, 42, 44, and 46 become heated and desorb selectedconstituents into a streaming sample fluid 530 and 630 at about the timewhen an upstream concentration pulse, produced by one or more upstreaminteractive elements, reaches the interactive element. Any number ofinteractive elements may be used to achieve the desired concentration ofconstituent gases in the concentration pulse.

Features of micro analyzer 500 may include: 1) Integrating into othermicro analyzers the approach to perform multi-level, multi-stagepre-concentration; 2) Having such approaches accomplished with twopumps, as in micro analyzer 500, except that the purpose for thelow-pressure pump was then to simply accelerate the filter purge rate,while here one may take advantage of it as a way to reduce the 1st-levelpre-concentrator soak time; 3) Performing the 1st-levelpre-concentration in such a way that its output can serve briefly as ahigher concentration analyte source for the 2nd-level pre-concentrator,which may be of the multi-stage type; 4) In cases requiring extremesensitivity (e.g., for analytes present in sub-ppt levels), performingthe 1st-level pre-concentration in such a way that its output may servebriefly as a higher concentration analyte source for the 2nd-levelpre-concentrator, which in turn may serve as a higher concentrationanalyte source for the 3rd-level pre-concentrator, which may be of themulti-stage type; 5) A 1st-level pre-concentrator that is not simply avery long channel (˜100× longer than previously disclosed multi-stagepre-concentrators, if G=100 is the concentration gain achievable at eachadsorption-desorption stage) to serve as 100× higher concentrationanalyte saturation source for the final pre-concentrator level, whichmay result in a far too high a pressure drop, but one that consists ofseveral channels in parallel to achieve a pressure drop that is muchlower than that of the final pre-concentration level; 6) Achieving thatlow pressure drop by widening the pre-concentration channels, heatersand adsorber films without sacrificing desirably low volumetric ratiosof gas/stationary phases; 7) Achieving that low pressure drop byincreasing the thickness of the adsorber film, without unduly increasingthe desorption time but decreasing desirably low volumetric ratios ofgas/stationary phases; and 8) Being able to operate micro analyzer 500structure in a flexible way, e.g., to meet the requirements forlow-sensitivity analyses without operating the parallel 1st-levelpre-concentrators, and/or without the second separator (μGC #2) if suchultimate separation is not required.

GC #1 and GC #2 may refer first and second fluid or gas chromatographs,respectively, of a micro analyzer. The first and second separators,which may be regarded as columns #1 and #2, respectively, may be a partof GC #1 and GC #2, respectively, along with the other components of themicro analyzer.

The advantages of micro analyzer 500 may include: 1) Very short analysistime (due to thin-film-based stationary film support) for μGCs of suchselectivity, peak capacity and sensitivity; 2) Achieving thehighest-possible sensitivities (due to very high PC levels) withoutcompromising selectivity or analysis speed; and 3) Simultaneousachievement of the highest-possible sensitivity, selectivity and lowenergy-per-analysis capabilities (by virtue of using two separate pumpsfor the low-pressure purge and soak function, and a higher pressure onefor the final pre-concentration level and separation functions).

FIG. 21 shows a micro analyzer 600 having a GC-GC type two-dimensionalstructure. A sample gas stream 630, which may also serve as a carriergas, may enter an input of a particle filter 627 and be pumped by pump640 via two parallel channels. In the main channel, fluid 630 mayproceed through a micro detector 631 and concentrator 623, respectively.Concentrator 623 may have an about 100 micron diameter. Fluid 630 mayflow from concentrator 623 through a flow sensor 632 and into aseparator 624, which may have an about 100 micron inside diameter. Fromseparator 624, fluid 630 may split to flow through a second separator625 and a micro detector 633. Separator 625 may have an about 50 microninside diameter. The fluid 630 output from separator 625 may go througha micro detector 634 and an orifice 644. The fluid 630 output from microdetector 633 may go through a micro valve 641 via line 643. The flow offluid 630 from a “T” connection at the output of filter 627 pumpedthrough line 646 may be controlled by orifice 645. Control,microcontroller or processor 635 may connected to pump 640, microdetectors 631, 633 and 634, flow sensor 632, concentrator 623,separators 624 and 625 and micro valve 641 to effect appropriateoperation of analyzer 600. Each of micro detectors 631, 633 and 634 maybe a TCD, MDD, PID, ECD or another kind of detector. Analyzer 600 mayhave more or fewer detectors than those shown. It may also haveadditional valves and other components. In other embodiments, microvalve 641 may be eliminated, so that only an uncontrolled pump andcritical-orifice flow regulation remains.

The main channel is disclosed in the present specification and thesecond channel, embodying the second μGC, is “sampling” the emerging andrelatively broad (half-width of μGC #1peaks˜total “free” elution time,t_(o), of μGC #2).

What cannot be separated via a micro fluid analyzer structure entailingtwo or more separation film materials built into its integratedstructure, may be realized here with an expanded, classical GC-GCstructure. A relatively slow-moving 1st GC may generate peaks with ahalf-width of 10–30 ms, which may get analyzed by a pulsed 2nd GC every20–100 ms, either on a timed or on a demand basis triggered by adetector at the end of that 1st GC. The second GC may additionally focusthe inlet peaks via rapid (˜1 ms) heating and cooling of its firstheater element, so that its electronically- or micro valve-controlledinjection peaks have a half-width of no more than ˜1 ms.

In embodiment #1, analyzer 600 of FIG. 21, the flow of μGC #1may becontrolled by an active micro-valve 641, while flows through the bypassand column #2may be controlled, i.e. set, by fixed orifices such as 634and 645. In embodiment #2, micro valve 641 may be replaced by anadditional, fixed orifice flow control.

In embodiment #3, all of the fluid 630 flow of μGC #1may flow into μGC#2; the flow may be controlled by one fixed orifice 647 before pump 640(of high but uncontrolled speed), and automatically accelerated upontransitioning to the cross section of column #2, after another fixedorifice/restriction 648 if needed, see FIG. 22.

FIG. 23 shows a micro analyzer 620 having two pumps 621 and 622 forbetter pumping of fluid 630. Adjacent to flow sensor 632 may be aseparator 651 having an about 140 micron inside diameter. Flow 630 fromseparator may go through a micro detector 652, a micro detector 652 andan orifice 653, respectively. From orifice 653, fluid 630 may go througha separator 654 having an about 70 micron inside diameter. Fromseparator 654, fluid 630 may go through a micro detector, an orifice 656and line 657, respectively, and onto pump 622. Optionally, there may bea micro valve 561, 661 connected to separator 525, 625 and 654 ofanalyzer 500, 610 and 620, respectively.

In all cases, the broad peak being sampled may be “injected” into μGC#2via and after a brief focusing period with the help of a short 1stadsorption element in the μGC #2 column, preferably made with stationaryphase film material and the thickness of column #1. Its subsequent rapidheating and desorption may be used to inject that analyte into μGC #2,which may feature a narrower column, higher velocity and thinneradsorption film to approach the higher optimal velocity for maximumresolution of μGC #2. That higher velocity may also be implemented bythe lower pressure in that column, either via the large pressure dropthroughout the column #2or via a fixed orifice (not shown in FIG. 21) atthe junction between the end of above element #1of column #2and theremainder of column #2 or at the junction between columns #1and #2.

During operation, the focusing process may be repeated either at fixedtime intervals or only when column #1detector senses a peak. Such afocusing operation may then start with a sharp drop in the temperatureof that 1st element of column #2, for a period of typical 2×Δt the peakhalf-widths, e.g., 2×20 ms (see the table 1 in FIG. 24). After such aconcentration period, t_(c), the adsorbed analyte may be rapidlyreleased, to result in peak half-width of about 2 ms. Other features ofthe exemplary data listed in FIG. 24 include the flow rates of samplegas in columns #1and #2, V, which may need to be equal, for embodiment#3; the concentration time, t_(c)=t_(o)(#2)=2Δt(#1); the velocity of thesample gas, v, may need to be close to the optimal one to maximize theresolution, R=t_(R)/Δt, for a middle range of 0≦k≦5, withk=(t_(R)−t_(o))/t_(o); and the time for desorption off the 1st elementof column #2(or last element of column #1), ˜Δt/2, may need to becompatible with the local flow velocity, so that 1/v≦Δt(#2)≦2 l/v.

The probability of false positives may be reduced because the number ofindependent measurements (i.e., resolvable peaks, or total peakcapacity) may be much larger with a μGC-μGC-μD, especially if the μD isa multi-channel detector such as a MDD, μECD, μFD (μfluorescentdetector). If the total peak capacity of μGC #1is ˜50, that of μGC #2is˜30 and that of an MDD is ˜10, the total number of independentmeasurement may be 50×30×10=15,000.

Features of micro analyzers 600, 610 and/or 620 may include: 1) Anintegration of a multi-stage pre-concentrator (PC)-μGC-μGC-detector onone chip, with options of further integration of additional detectors,and possibly more importantly the use of an optimal mix and synergy ofmaterials for the PC, GC #1and GC #2films and the micro detector, μD, sothat interferents that the μD is sensitive to are not retained and/ornot pre-concentrated, but targeted analytes get pre-concentrated andwell separated; 2) A smart and flexible operation of one or both μGCs ofthe present micro analyzer, e.g., with a user selection of the number orfraction of total heater array elements to function as pre-concentrators(PC) vs. separators (S), and/or with user-selection of the type ofcompounds chosen and desorbed from which pre-concentrator material (asopposed to desorbing all materials from various pre-concentratorelements); 3) A design of item 1) of this paragraph that retains its(palm-top to cubic-inch type) compactness, 3-second analysis, ≦ppbsensitivity, flexibility, smartness, integrated structure, low-power,valve-less electronic injection and overall low-cost feature; 4) Adesign of items 1) and 3) of this paragraph, whereby the shown andactive micro valve 641 in FIG. 21 may be eliminated, so that only anuncontrolled pump and critical-orifice may remain for flow regulation;5) A design according to items 1 through 4 of this paragraph, wherebythe mass flow rates through μGC #1and #2may be equal, but these columns(and fixed pressure drop orifice or nozzle at the end of column #1) maybe configured (ID, pump capacity and other fixed orifices to controlpump speed through a sonic nozzle) to raise the flow speed by ˜3–10× thelevel of column #1, to enable an approximately complete (within a timeof about t_(o) to 2t_(o)) analysis to be done by column #2within thetime of the half-width of the peaks eluting from column #1, and mayfeature an adjusted adsorber film thicknesses, to optimally meet thevalues for Golay's equation; 6) Achieving operation of micro analyzer600, 610 and/or 610 by “focusing” a complete peak from column #1(seeFIG. 24, Δt=20 ms) within a suitable (same or preferably ˜half-sized)element, and a time of 2Δt, so it can be desorbed and flushed within atime, Δt2 ˜1–2 ms; 7) The use of two pumps, 621 and 622 in FIG. 23, eachdesigned for pumping at a particular flow rate and suction pressure,rather using one pump that may have to both satisfy the largest massflow, pumping time and pressure requirement of the two tasks; 8) Theintegration and use of many types of integrated detectors, to reduce theprobability of false positives, which decreases as one may increase thenumber of independent measurements, preferably by embedding of twoseparate functions into the micro analyzer—selectivity (via aspectrometric function, e.g., to separate analytes on the basis of theiroptical absorption, mass, boiling point, etc. properties) andsensitivity via a non-selective but very sensitive detector.

Advantages of the micro analyzer embodiment #3 may include:

-   1) A μGC-μGC combination to enable greater resolution and thus more    complete analysis for a marginal increase in cost for the extra mask    and deposition of a different adsorber film material;-   2) A cost reduction based on eliminating an active valve and    managing proper synchronization via small adjustments in the    electronically controlled rate of the “heater-wave” propagation;-   3) A further cost reduction due to a reduction in the calibration    accuracy previously needed for the flow sensor (the flow may be    roughly measured and adjusted with the aid of this flow sensor, but    the optimal synchronization may be accomplished as described in item    #2 of this paragraph) via electronic adjustment of the heater    rate; 4) A further cost and maintenance reduction by using a pump    capacity 20–80% higher than needed (at the same cost), but saving    the control design and debugging effort involved with pump rate    control (the excess capacity may be simply controlled via the flow    limited by the fixed orifices); 5) The use of two pumps 621 and 622    as in FIG. 23, each designed for its task, is more efficient than    using one pump that has to both satisfy the largest flow rate,    pumping time and pressure requirement, and can save the cost and    design effort of an additional orifice; and 6) The contribution of    each n_(i) in the system composed of the m-chain of elements    PC-μGC-μGC-μD3 . . . μDm may help minimize the probability of false    positives, P_(fp), where    1/P _(fp)=[1−exp{−(R _(SN)−1)/4}](n ₁ , n ₂ , . . . n    _(m))^(0.8)(Y+1),    and R_(SN)=signal/noise ratio, n₁, n₂, n₃, . . . n_(m)=the number of    independent measurements or elimination criteria (e.g., filtering    steps via selective PC elements, spectrometric resolution elements    via μGC #1and μGC #2or measurement channels via each of several    different μD_(j)) and Y=1/P, the inverse probability that a    particular false positive, once registered, can be confirmed as such    via redundant sensors, repeat measurements, neighboring sensors in a    sensor grid, and/or an occurrence of appearances of interferents of    unusually high cross sensitivity.

FIG. 25 is a diagram of an HPLC/CLC micro-analyzer 701. HPLC indicateshigh-pressure liquid chromatography and CLC indicates capillary liquidchromatography. Analyzer 701 may have an inlet particle filter 702 forfiltering an input sample stream 710 that may be split into streams 711and 712 being input into the analyzer. Steam 711 may proceed through athermo-conductivity (TC) detector 702. After detector 702, analytes ofstream 711 may be concentrated by concentrator 704 having phased heaters20, 22, 24, 26 and more of the same as designed. Stream 711 may then gothrough a flow sensor 705 and on to a separator 706 where the analytesare separated by compound.

Flow 711 may then go through a TC detector 707. A controller 708 may beconnected to concentrator 704 for controlling the movement of the phasedheat pulse in the concentrator relative to stream 711. Controller 708may also be connected to separator 706, TC detectors 703 and 707 andflow sensor 705. With the information of the sensor and detectors, andinput signals to the concentrator and separator, information of thesample may be processed. Stream 711 leaving detector 707 may join upwith stream 712 at a “T” connection 709 to form an output stream 713.

A valve 714 may control the flow of stream 712 in proportion of the flowof stream 711 as it comes into connection 709. At the output of Tconnection 709 may be a pump 715 pulling in stream 713 to be output frompump 715 and analyzer 701. Valve 714 and pump 715 are connected tocontroller 708 which controls the flow of stream 711, with valve 714 andpump 715, through the concentrator at a particular rate for appropriatephased heating to maintain the increasing heat pulse in stream 711 as itmoves through concentrator 704.

Aspects of the present PHASED micro analyzer include its dual use forboth liquids and gases. These aspects are described below with the aidof FIGS. 6 c, 6 d, 26 a and 26 b, while FIG. 25 represents the systemfor all of these.

FIG. 6 b shows a reference design 41 of a phased heater (PHASED) microanalyzer. This figure is a cross-sectional view of the phased heateranalyzer, versions I and II, showing an exposed membrane 716 which mayhave a thickness of about one micron. The exposure of membrane is intoopening 392. Membrane 716 may composed of silicon nitride (Si3N4) withPt heater(s) 20, 22, . . . inside the membrane. This design may beprimarily for initial analysis of gaseous analytes, because itsmembrane-based heater elements might not withstand more than about 50psi (≈3.5 bar) relative to ambient.

FIG. 6 c shows the PHASED III (i.e., version III) micro analyzer. Thisdesign is not constrained to the 50 psi (≈3.5 bar) maximum pressure inmicro channel 32, relative to ambient, as the FIG. 6 b reference designis. There is a similar design in FIG. 6 a except for having bothchannels 31 and 32 (above and below the membrane) of equal size and eachhaving an absorber coating 140 and 40. The approach of FIG. 6 c mayresolve the problem by making the lower channel 394 just deep enough forthermal isolation and relying on mass diffusion to equilibrate the topand bottom gas concentrations. When used with liquids, there may be anissue about whether membrane 716 would be sufficiently rugged and havefast enough liquid diffusion rates.

FIG. 26 a shows a micro-brick based design 720 of analyzer 701 which maybe regarded as Microbrick™ micro analyzer or a PHASED IV analyzer. Thisdesign has a feature that may eliminate the concern about ruggedness anddiffusion rates, when used with liquids. As shown, the ruggedness isachieved by building the array of heater elements 20, 22, 24, . . . ,membrane 716 (e.g., which may Si₃N₄ with Pt heaters inside), dielectric717 (e.g., which may be SiO₂) and sensors on a solid (micro) substrate718, (i.e., solid like a brick—thus, micro-brick which may be calledMicrobrick™) which may consist of Si, silica (SiO₂), Pyrex™, a thickcoating of silica on silicon water, polymers, or other sufficientlystable, heat resistant but thermally insulating materials. Substrate 718may have heaters. The tradeoff for this ruggedness may be about 3 to 8times increase in the specific power consumption. There was measured adrop in the heating ability from about 20 to 10 degrees, and to about 2degrees C/mW between micro-bridge, micro-membrane and micro-brick flowsensor designs, respectively. For a micro-membrane-based PHASED device,there was a measured 0.43 degree C/mW for each 5000×100 micrometerheater element. Because the allowed heater temperature rise in liquidsmay be about 4 to 10 times lower than in gases, then it may beanticipated that the power demands of the switching elements and circuitwill remain about the same if this structure is used to analyze liquidswith heater temperature rises not exceeding 20 to 25 degrees C, butabout 4 times higher for gases using temperature rises of up to 200 to250 degrees C relative to design 41 of FIG. 6 c. Layer 717 may be formedon wafer 718.

FIG. 26 b reveals a capillary-based design 730. One possible shortcomingof the micro-channel designs in FIGS. 6 b, 6 c and 26 a is that theabsorber film 40 only covers one of the four sides of the rectangularchannel 32, which increases the volumetric mobile/stationary phaseratio. This ratio should not influence the resolution or elution time(assuming constant film thickness) but can influence the sensitivity ifthe stationary volumetric “absorber capacity” is too small relative tothe volume of the mobile phase. For optimal use of a channel, it maytherefore be desirable to have the largest possible internal surfacecovered with adsorber film, which should be as thin as possible,provided it does not lower the sensitivity. FIG. 26 b showsschematically one such design 730.

Capillary 730 with an exemplary inside diameter of 100 micrometers andan outside diameter of about 300 micrometers may be coated internallywith the desired GC film material 732, such as an appropriate adsorbermaterial, and thickness. On the outside (or inside under the adsorbercoating), a uniform resistive heater film 731 may be deposited, inexemplary segments 735 of 5 millimeters in length 733, which areseparated by an electrically non-conducting gap 734 of 100 micrometers.As each element is heated in the basic phased design and operation, thecapillary segments 735 may be heated, of pre-concentrator 704 about 5milliseconds each, before switching to next element 735. The dimensionsof capillary 730 and its components may be different than as statedhere.

Capillary 730 may have application in the structure of the fluidanalyzers describe in the present description. For separator 706, thetemperature may be programmed to rise to reduce the elution time of theheavier analytes. Smaller elements may be used for flow sensor 705,thermal conductivity detectors (TCDs) 703 and 707, and an electricalconductivity detector (ECD) if used. The EDC may be used in an AC modeto sense electrical conductivity through a capillary wall 736 (only ifthe wall is electrically non-conductive). Flow sensor 705 and TC sensors703 and 707 may also be used to measure flow and thermal conductivitythrough capillary wall 736 (electrically conductive or not).Alternatively, the heater film 731 can be deposited under GC film 732 onthe inside of capillary 730, and thus avoid increases in the responsetime, up from the ≦1 millisecond measurable for the micro-bridge andmicro-brick designs, when they are separated from the gas only by theabout 0.5 micrometer thickness of the silicon nitride. Another heaterfilm structure 731 may be one that is continuous throughout capillary730 and features conductive metal film-rings 735 about 100 micrometerswide and about 5 millimeter intervals, so that the switching circuit canenergize one segment for about 5 milliseconds at a time, as in a movingwindow (this feature may be more manufacturable if the heater film is onthe outside). Conductive rings 735 would also be solder-bumped ontocorresponding bumps on a printed circuit board (PCB) 737. PCB 737 mayhave switching circuitry for sequentially switching electrical power toheater elements 735 for providing a heat pulse in sample liquid 711heating flowing through a capillary 730 in analyzer 701. Capillary 730may be straight if a length of 10 to 15 centimeters is sufficient orshaped as an “8” or “0”, as meanders or a (tubular or flat) coil windingwith electrical contacts only at zero degrees, or also at 180 degrees,or every 90 degrees or every reasonable distance of 1–5 mm, to allow forthe finite minimum radius of quartz or steel capillary radius ofcurvature. In this way, capillary lengths of up to 100 centimeters canbe made compact and compatible with the 40 to 200 points of electricalcontact on PCB 731.

Implementation of such capillary heaters 735 on stainless steel may justrequire deposition of the conductive rings spaced every about 5millimeters, if the resistance of the stainless material can be used asa heater. In the case of quartz capillaries, connections to an internalarray of heating elements would require the use of emerging TTW (throughthe wave) soldering technology. An easier manufacturing method maytherefore be based on external application of the heater film 731. Theinternal thin-film heater film option may be heated via microwavecoupling to its thin-film, electrically conductive material.

To implement any of the above designs, one may need stable, long-lifeand repeatable flow control, so that multi-stage pre-concentration canbe effective. Developmental piezoelectric, electrostatic andelectromagnetic valves and pumps may be available. One approach toachieve optimal performance may be to select a capillary column 730 fora pre-concentrator 704 and separator 706 but fit the end of capillarystructure 735 into the input and output ports of a sensor ofdifferential thermal conductivity and differential electricalconductivity. According to Golay's equation, the optimal water velocityfor a 25-centimeter-long, 100 micrometer inside diameter column, with a0.6 micrometer film would be about 10 centimeters per second, whileovercoming a pressure drop of 15 psi (˜1 bar), and would achieve aresolution of 15:1 (D_(s)=0.00001, D_(m)=0.01 cm²/sec).

Golay's equation may take the following form:

$H = {\frac{2D_{m}}{u} + {\frac{( {1 + {6k^{\prime}} + {11k^{\prime 2}}} )r^{2}}{24( {1 + k^{\prime}} )^{2}D_{m}}u} + {\frac{k^{\prime 3}r^{2}}{6( {1 + k^{\prime}} )^{2}K^{2}D_{s}}u}}$where H is the variance per unit length of the column for the givensolute, k′ is the capacity factor of the solute, K is the distributioncoefficient of the solute between the two phases, D_(m) is thediffusivity of the solute in the mobile phase, D_(s) is the diffusivityof the solute in the stationary phase, r is the radius of the column,and u is the linear velocity of the mobile phase.

The PHASED-based HPLC/CLC micro analyzer 701 may include the followingfeatures. One feature may be liquid chromatography application of aphased, multi-stage pre-concentration and electronic injection,integrated functions of such pre-concentration, injection, separation,flow sensing and detection, insertion of spin-on coating materials forstationary phase during fabrication, use of integrated vacuum packaging(IVP) technology for fabrication of the sample flow channels, and use ofthe bulk sample liquid as a advantageous carrier liquid, and the use ofthermal micro-sensor technology for the fabrication of direct orindirect flow and TC sensing.

A particular design of the capillary 730 column for the functions ofpre-concentration, separation, flow sensing, and thermal and electricaldifferential conductivity sensing, may be based on (see FIG. 26 b)various characteristics. One may be involve micro-bridge technology(immune to high pressure) as an approach for IVP-integration of columnand sensors, with adsorber on one side of the bridge and one main sampleflow channel. However, micro-membrane technology by itself may notsurvive application of liquid pressures beyond 50 psi (≈3.5 bar). Thedevice may involve micro-brick technology for IVP-integration of columnand sensors. Another characteristic or feature may include one or moreturns of a quartz or steel capillary, with external coatings for heatersand sensors, and contact-bonded to a circuit with appropriate heaterswitching means and sensor input/output circuits (I/Os).

One approach may be to synchronize the energy pulses to the elements ofthe heater array as the analyte wave velocity accelerates and expands asit is drawn through the pressure drop of the pre-concentrator, based onsensing the half-width of a detector peak and adjusting the flow rate tominimize that width.

The advantages of micro-analyzer 701 over the traditional HPLC/CLC mayinclude a 100 to 1000 times increase in sensitivity by virtue of themulti-stage pre-concentration. The operation of PHASED micro analyzer701 may be without carrier fluid, for greater ease of use, higherreliability and lower cost, and because the cost of present simpleelectronic injection is much less than injection relying on lessreliable and more complex and higher-energy consumption mechanicalvalving. The traditional HPLC/CLC operation may involve the use of anon-conductive carrier liquid into which a small sample volume isinjected via mechanical valving. The use of carrier fluid with PHASEDmicro analyzer 701 may be optional. If a carrier fluid is used in thepresent analyzer, the carrier fluid and sample fluid may be continuouslymixed. The effectively diluted analyte concentration may be re-gained(and exceeded) during the sample pre-concentration steps. The analyzer701 of the micro-brick 720 or capillary 730 configuration is very rugged(environmentally and structurally) and able to analyze liquids or gases.HPCL/LC/GC analyzer 701 may not necessarily require Si machining.

Although the invention has been described with respect to at least oneillustrative embodiment, many variations and modifications will becomeapparent to those skilled in the art upon reading the presentspecification. It is therefore the intention that the appended claims beinterpreted as broadly as possible in view of the prior art to includeall such variations and modifications.

1. A fluid analyzer comprising: a concentrator having a firstsolid-state thin-film heater-adsorber support channel of solid support;a phased heater array proximate to the first solid-state thin-filmheater-adsorber support channel; and a separator having a secondsolid-state thin-film heater-adsorber support channel connected to thefirst solid-state thin-film heater-adsorber support channel.
 2. Theanalyzer of claim 1, further comprising a controller connected to theconcentrator and the separator.
 3. The analyzer of claim 2, furthercomprising at least one detector connected to the controller.
 4. Theanalyzer of claim 3, wherein the first and second solid-state thin-filmheater-adsorber support channels are for concentrating and separating afluid having a pressure greater than 50 psi (≈3.5 bar).
 5. The analyzerof claim 4, wherein the first and second solid-state thin-filmheater-adsorber support channels are for concentrating and separating afluid subject to a pressure of up to about 10,000 psi (≈700 bar).
 6. Theanalyzer of claim 5, wherein the heater array comprises: a plurality ofheaters in a row along a direction of flow of a fluid to be analyzed;and each heater of the plurality of heaters may be turned onsequentially at a rate of movement in a direction equivalent to a flowof a fluid to be analyzed.
 7. The analyzer of claim 6, wherein the firstand second solid-state thin-film heater-adsorber support channels have asubstrate of a micro-brick structure comprising at least one materialfrom a group of Si, SiO₂, glass, quartz, sapphire, steel and the like.8. The analyzer of claim 7, wherein the first and second solid-statethin-film heater-adsorber support channels comprise a sufficientlystable, heat resistant and thermally insulating material.
 9. Theanalyzer of claim 6, wherein the first solid-state thin-filmheater-adsorber support channel with segmented heaters is a capillary.10. The analyzer of claim 9, wherein the capillary has an inside surfacecoated with an absorber material.
 11. The analyzer of claim 10, whereineach heater of the plurality of heaters is formed as a film segment on acapillary wall.
 12. The analyzer of claim 11, wherein the capillarycomprises a material from a group of glass, quartz, sapphire, steel andthe like.
 13. The analyzer of claim 9, wherein the second solid-statethin-film heater-adsorber support channel is a capillary.
 14. Theanalyzer of claim 13, further comprising a flow sensor proximate to atleast one solid-state thin-film heater-adsorber support channel.
 15. Theanalyzer of claim 14, comprising an electrical conductivity detectorproximate to at least one solid-state thin-film heater-adsorber supportchannel.
 16. The analyzer of claim 15, further comprising a hyperconcentrator having a third solid-state thin-film heater-adsorbersupport channel connected to the first solid-state thin-filmheater-adsorber support channel.
 17. A fluid analyzer comprising: afirst channel having a plurality of heaters; and a second channelconnected to the first channel; and wherein: the first channel has astructure sufficient to withstand an internal high pressure; the secondchannel has a structure sufficient to withstand an internal highpressure; and the internal high pressure is greater than 10,000 psi(≈700 bar).
 18. The analyzer of claim 17, further comprising: at leastone thermoconductivity detector situated in at least one channel; and atleast one flow sensor situated in at least one channel.
 19. The analyzerof claim 18, further comprising a controller connected to the firstchannel, the second channel, the at least one thermoconductivitydetector, and the at least one flow sensor.
 20. The analyzer of claim19, wherein the first channel comprises at least one interactive elementcorresponding to each heater element of the plurality of heaters; andthe plurality of heater elements may be energized in a time phasedsequence to heat the corresponding at least one interactive element. 21.The analyzer of claim 20, wherein each corresponding interactive elementmay absorb and desorb constituents of a fluid in the first channel. 22.The analyzer of claim 21, wherein the second channel may separate afluid by compound.
 23. The analyzer of claim 22, wherein the firstchannel is a first capillary.
 24. The analyzer of claim 23, wherein thesecond channel is a second capillary.